1. Field of the Invention
The invention relates to controlling movement and speed of trains on railways, and more particularly to a user interface that assists train operators to optimize throttle and brake application of train speed controls. As used herein, the term “train” is a locomotive alone, one or more locomotives with cars, or an integrated locomotive/car vehicle, (e.g., light rail or subway).
2. Description of the Prior Art
Rail lines establish maximum local operating speeds along the track right of way, dictated among other things by track conditions, train line congestion and distances ahead of trains that are needed for braking and acceleration to different speeds. Railway operators also establish points of interest along the railway tracks that suggest minimal or optimal speeds for local track conditions, efficient energy usage and travel scheduling. Other or units exist along the railway tracks that mandate maximum speeds or need to stop completely. Points of interest, may be fixed and marked by trackside signals (e.g., visual signage, sensors, and/or wireless transmitters). Points of interest may also be varied depending upon operating conditions, and communicated to the train operators via reconfigurable electronic signage or wireless transmission.
Electronic onboard and/or remote oversight of train operation is becoming more prevalent in order to optimize system-wide operation based on changing conditions and reduce likelihood of human error caused incidents. So-called Positive Train Control (PTC) Systems provide for onboard and remote monitored automatic train operation supervision and control by an electronic Onboard Unit (OBU). The OBU is coupled to or incorporated within the locomotive train control system, sometimes referred to as the train management system (TMS). The TMS OBU automatically slows or stops a train that exceeds local speed restrictions or fails to obey a stop signal. The most aggressive OBU control operation is complete stopping of a train that exceeds maximum local speed limits or fails to stop at a designated stopping point. Energy and scheduling time are wasted when an OBU forces a train to come to a full stop from steady state operating conditions, ascertain the events causing the stop, and restart the train back up to operating speed.
Train operation is complex; among other reasons due to momentum force-induced response phase lags during acceleration and deceleration of a relatively heavy vehicle on a fixed, relatively narrow track path. Through operational experience accumulated over time, a train operator develops intuitive judgment when to apply train throttle and brake settings of the train speed controls to meet changing operating conditions and upcoming new speed restrictions. Human interface guidance tools have been developed to assist train operators in making decisions when and how to apply throttle and brake settings.
FIG. 1 shows one known train operator interface 20 that graphically gives the operator feedback about train track 21 relative position of a train 22 and a critical point 24 that may be a stop signal, track switch, change in local speed, etc. A train stopping distance bar 26 (often visually displayed as a vertical red colored bar) moves between the train 22 and the critical point 24 and signifies actual distance needed to bring the train to a different new lower speed or a full stop. A warning distance yellow vertical bar 28 also moves, and signifies a warning time interval ahead of the stopping distance bar 26. If the warning distance bar 28 reaches the critical point an audio and/or visual enunciation warning will be given to the train operator to take action to bring the train to the required operating state (e.g., stop or mandated lower maximum speed) before the OBU undertakes its own automatic action. In using the prior art interface 20 the operator's goal is to make sure that the warning distance bar 28 does not reach the critical point 24, so as to avoid both alarm enunciation and OBU automatic intervention. However, the interface 20 does not give the train operator feedback on train speed brake and/or throttle settings needed to conform the train the required operating conditions before the warning distance bar 28 reaches the critical point 24: in other words, when and how much to apply throttle or brake.
Another known type of train operator interface is a display screen configured in accordance with European Railway Agency (ERA) Standard ERA_ERMTS—015560, as shown in FIGS. 2-4. The display screen 30 includes a distance to critical point target guide portion 32, with an analog relative distance scale portion 34, a digital distance to target display 36, and an analog distance bar 38 that is proportionally sized to the distance scale 34. As was also a challenge when using the interface 20, the train operator does not perceive direct feedback from the target guide portion 32 when or how much brake or throttle to apply, nor their respective appropriate application timing.
In order to give the train operator guidance on permissible local train speed—but not how to actuate the throttle and brake controls to achieve a permissible speed—the ERA display screen 30 has a speedometer or “tacho” 40, with a circular analog speed calibration ring or scale 42, a moving color-changing analog pointer 44 and a digital speed readout 46 located in the pointer hub portion. A series of sequential color-coded arcuate speed status bands 50, 52, 54 are displayed on the periphery of the speed scale 42 and change in length to correspond to changes in local permissible speed conditions.
Normal status speed band 50 (color-coded gray) indicates the permissible localized speed range. Indicator status band 52 with maximum speed status limit line 53 (color-coded yellow in FIG. 2 along with the speedometer pointer 44) informs the train operator that the train is exceeding normal permissible speed, so that he or she can undertake steps to slow down the train. Overspeed/warning status band 54 (color-coded orange in FIG. 3 along with the speedometer pointer 44) warns the operator that the OBU will intervene in and override operator train speed control by applying train brakes unless the operator undertakes immediate steps to slow down the train. Should the train speed exceed the intervention speed the OBU will apply train brakes to bring the train to a complete stop, and will so indicate intervention mode with status band 56 (color-coded red along with the speedometer pointer 44).
While the ERA user display 30 speedometer 40 does apprise a train operator of permissible local speed ranges and the target guide portion 32 the distances to critical points, it does not give the train operator guidance on how to set the throttle and brake controls to reduce train speed. The train operator must make her or his determinations whether and how much to apply brake or throttle in order to operate the train within, speed limits indicated by the status bands 50, 52, 54 and 56.
Thus, there is a need for a train operator user interface that gives guidance to the operator when and how much to apply brakes and throttle to conform the train to local operating speed restrictions, so as to avoid automatic intervention by the OBU.
There is an additional need for a train operator user interface that helps the operator intuitively understand brake/throttle corrections needed to conform the train speed to local operating speed conditions and give visual feedback when the proper corrections have been made.